Forced flow steam generator



April 1964 R. F. DAVIS 3,129,698

FORCED FLOW STEAM GENERATOR Filed March 15, 1961 3 Sheets-Sheet 1 Fly.1'

April 21, 1964 R. F. DAVIS FORCED FLOW STEAM G ENERATOR 3 Sheets-Sheet 2Filed March 15, 1961 Jn mania r': PEG/MAL D FDA W5.

April 21, 1964 R. F. D AVlS FORCED FLOW STEAM GENERATOR I s Sheets-Sheet3 Filed March 15, 1961 5. 3 WF 1 m 9 W a r I W a K I P N a 8 \& 2N w/Na/R \8 2 8 @N w 4;; 3 W f a 1 H M p U mm 2 mqmw 2 a 4, W N n Q mu m r K9 United States Patent 3,129,698 FGRCED FLGW STEAM GENERATGR ReginaldFrank Davis, Littieover, Derby, England,

assignor to Suizer Freres, S.A., Winterthnr, Switzerland,

a corporation of Switzerland Filed Mar. 15, 1961, Ser. No. 6,15 Claimspriority, application Great Britain Mar. 18, 1960 8 Claims. (Cl.122-510) The present invention relates to forced-flow steam generatorsand particularly to the combustion chamber structure thereof.

It is an object of the invention to provide in a forcedilow steamgenerator a furnace whose walls are formed by tangent serpentine tubesand yieldable under changing temperature conditions.

Difiiculties were encountered with combustion chamber linings of theaforedescribed type, particularly if the combustion chamber casing andits insulation are supported by the tubes.

According to the invention the tubular furnace walls of a forced-flowsteam generator are carried by substantially vertical support tubesserving as feeder tubes and arranged at the corners of the furnace, eachfurnace wall comprising a series of serpentine tubes to which operatingfluid is supplied by said feeder tubes. The feeder tubes are hung on asupporting framework and the tubes forming the side walls of the furnaceare connected to supporting frames composed of bars and plates, saidframes being partly rigidly and partly slidingly connected to tubesforming the furnace wall as well as to the vertical support tubes toafford expansion and contraction under varying temperature conditions.

The novel features which are considered characteristic of the inventionare set forth with particularity in the appended claims. The inventionitself, however, and additional objects and advantages thereof will bestbe understood from the following desacription of embodiments thereofwhen read in connection with the accompanying drawing wherein:

FIG. 1 is a diagrammatic rear view of a combustion chamber wallaccording to the invention with parts broken off or removed and showingonly one supporting frame.

FIG. 2 is a horizontal sectional view of tubes near a corner of acombustion chamber one wall whereof is shown in FIG. 1; the section ismade along line AB in FIG. 1.

FIG. 3 is a vertical sectional view of a support frame with combustionchamber wall tubes connected thereto, the section being made along line0-D of FIG. 1.

FIG. 4 is a vertical sectional view of a support frame showing itsconnection to a vertical corner tube, the section being made along lineEF of FIG. 1.

FIG. 5 is an elevation of a portion of a group of tubes in theneighborhood of a rectangular bend at the transition from the verticalsupport tubes to the horizontal wallforming tubes.

FIG. 6 is a horizontal sectional view taken along line GH of FIG. 1, ofone of the four corners of a rectangular combustion chamber. The othercorners, not shown, are constructed in the same manner as theillustrated corner.

In the illustrated example an evaporating tube section 1 is provided oneach wall of a combustion chamber whose horizontal section issubstantially rectangular. Only one wall formed by one evaporating tubesection and four vertical tubes of a second evaporating section areshown in FIG. 1. Each tube section is formed by a group of sevenjuxtaposed tubes, four of the tubes being numbered 2, 3, 4, 5. The tubeshave horizontal portions forming panels, the tubes of one panel beingconnected by vertical or hairpin-like portions to the tubes of thepreceding and of the subsequent panels. The tubes are continuous andextend in serpentine fashion from the bottom end to the top end of therespective wall. Substantially vertical, laterally tangent tubes areplaced at the four corners of the furnace and form groups of seven tubesat each corner. In the illustrated example the diameter of the verticaltubes is greater than that of the wall forming serpentine tubes. Thevertical tubes at the right corner and visible in FIG. 1 are numbered 9,8, 7, 6, three more tubes being placed behind the tube 6. The tubes atthe left corner and visible in FIG. 1 are numbered 13, 12, 11, 6, threemore tubes being behind tube 6. The tubes of each group of verticalcorner tubes are individually connected to the tubes forming one wall ofthe furnace and serve to feed operating medium into the wall tubes. Thevertical tubes depend from a supporting framework or structure 34 andserve as supports for frames to which the tubes forming the furnacewalls are connected, To stabilize the relative position of theneighboring marginal tubes of the tubular wall panels grooveand-tonguejoints 14, 15 are provided as shown in FIG. 3. Similar joints 16, 17 areprovided between the vertical marginal tube portions of the wall panelsand the neighboring vertical corner tubes as shown in FIG. 2.

The weight of the tubular wall panels is transferred to the respectivevertical corner tubes by a framework including horizontal channels orU-beams 21 and 26 extending across the furnace walls. The horizontaltubes 2, 3, 4, 5 of each panel are welded to vertical rods 18 for fixingthe tubes in vertical planes. In order to permit relative expansion ofneighboring tubes the welds are arranged in staggered or offsetrelation, preferably two tubes being left unwelded between two weldedtubes. An upper lug 19 and a lower lug 21) are welded to every fourthrod 18. The lower channels 21 are supported by brackets 22 (FIG. 4)welded to the corner tubes. The channels 21 are provided with verticalwebs 23 parallel and corresponding to the lugs 20 which extend throughsuitable apertures in the Web of the channel 21. The adjacent lugs 20and webs 23 are connected by pins 24 connected to the lugs and extendingthrough vertical slots 25 in the webs 23 to permit relative verticalmovement of the lugs and webs. This construction also permits relativehorizontal movement of the lugs and webs.

In order to make the channels 21 more rigid the channels 26, which areplaced above and spaced from the channels 21, are connected to thechannels 21 by vertical T-irons or uprights 27. In addition, flat steelplates 23 are welded to and interconnect the channels and fill thespaces between the channels and the uprights 2'7. Bolts 39 mounted onthe lugs 19 and extending loosely through bores in spaced webs welded tothe channels 26, and placed normal to the lugs and webs transfer theweight of the panels to the channels 26 and permit relative h0rizontalmovement. The upper channels 26 are connected to the respective verticalcorner tubes by sliding points each joint comprising a lug 31 and a pin33 connected thereto, the pin extending through vertical slots 31 in theopposed end faces of the elements 26. These joints are similar to thejoints 24, 25 to permit relative vertical movement of the upper channelsand the respective corner tubes.

As seen in FIG. 5, short aligning bars 32 are alternately welded inoffset relation to the tubes forming the wall panels in the neighborhoodof the bends between the horizontal portions of the tubes and thevertical corner tubes. The bars 32 slidingly engage the respectiveneighboring tubes to fix the tubes in a plane while permitting relativelongitudinal expansion of the tubes.

Refractory sealing material 36 is applied to the back side of the tubepanels and is about as thick as the rods 18 in order to prevent escapeof combustion gas. Casing plates 35 are welded to the support frames inback of the refractory material and form, together with the plates ofthe support frames, a gastight skin provided with expansion joints andreinforcements in the conventional manner. Outside the skin casing is anouter casing containing insulating material for the boiler walls.

Horizontal strap elements are connected to the upper and lower channelsand extend from corner to corner of the furnace. The ends of theseelements are connected at the corners of the furnace to counteracthorizontal pressure caused by explosions within the combustion chamber.These strap elements are connected to the casing and to one another bybolt joints permit-ting relative movement in certain directions in amanner similar to that adopted in known designs of skin casing for otherthan forcedflow steam generators.

The support frames and the skin have, due to the outer insulation,substantially the same temperature as the fluid in the tubes and expandwith the tubes. In operation, the fluid temperature in the panel coilsincreases progressively and continuously from bottom to top of the steamgenerator. Therefore, the upper portions of the structure expand morethan the lower. The corner tubes have a lower temperature than the tubesof the wall panels because the operating fluid enters the top end of thecorner tubes. These temperature differences are rendered harmless by thesliding overlapping fin joints between the outer tubes of each panel andthe adjacent vertical corner tubes.

While a specific embodiment of the invention has been shown anddescribed, it will be apparent to those skilled in the art that variouschanges, modifications, substitutions, additions and omissions may bemade therein without departing from the spirit and scope of theinvention as set forth in the appended claims.

I claim:

1. In a forced-flow steam generator comprising a combustion chamber ofangular horizontal cross section and having a plurality of side Wallsand corners therebetween, a supporting framework, substantially verticaltubes placed in each corner of said combustion chamber and hung on saidframework, a plurality of said vertical tubes being placed in the planeof one of the side walls extending from the corner and a plurality ofsaid vertical tubes being placed in the plane of the second side wallextending from said corner:

tubes bent in serpentine fashion placed in planes and forming tubepanels forming the parts of said side walls between said vertical tubes,

at least one horizontal support frame for each side wall,

each of said support frames comprising a horizontal structural steelelement at the upper end of the frame, a horizontal structural steelelement at the lower end of the frame, and a steel plate placed betweensaid structural steel elements.

support brackets connected to said vertical tubes outside of thecombustion chamber for supporting one of said structural steel elements,

sliding connections vertically slidably connecting the second of saidstructural steel elements to said vertical tubes, vertically slidableconnections between said tube panels and one of said structural steelelements, and

horizontally slidable connections between said tube panels and thesecond of said structural steel elements.

2. In a forced-flow steam generator as defined in claim 1 and whereinthe lower of said structural steel elements rests on said supportbrackets.

3. In a forced-flow steam generator as defined in claim 1 and whereinsaid sliding connections vertically slidably connect the upper of saidstructural steel elements to said vertical tubes, said verticallyslidable connections are arranged between the lower of said structuralsteel ele- 4iments and said tube panels, and said horizontally slidableconnections are arranged between the upper of said structural steelelements and said panels.

4. In a forced-flow steam generator comprising a combustion chamber ofangular horizontal cross section and having a plurality of side wallsand corners therebetween, a supporting framework, a plurality ofsubstantially vertical tubes placed in each corner of said combustionchamher and hung on said framework, each of said side walls being formedby a plurality of tubes bent in serpentine fashion and placed in aplane, said wall-forming tubes being connected to said vertical tubes toreceive operating medium therefrom, at least one support frame for eachside wall, each of said support frames being composed of structuralsteel elements and steel plates, support brackets connected to saidvertical tubes outside of the combustion chamber, said support framesresting on said brackets, sliding connections slidably connecting saidsupport frames to said vertical tubes and to said wall-forming tubes,one of said support brackets and a lug being welded in axially spacedrelation to at least one of said vertical tubes in each corner, a webconnected to the support frame supported by said bracket, said lug andsaid web being placed side by side and in parallel relation, said webhaving a vertically slotted hole, and a bolt connected to said lug andextending through said slot-ted holes for holding said support frame tosaid vertical tube and permitting relative movement of said lug and saidweb.

5. In a forced-flow steam generator comprising a combustion chamber ofangular horizontal cross section and having :a plurality of side Wallsand corners therebetween, a supporting framework, a plurality ofsubstantially vertical tubes placed in each corner of said combustionchamber and hung on said framework, each of said side walls being formedby a plurality of tubes bent in serpentine fashion and placed in aplane, said wall-forming tubes being connected to said vertical tubes toreceive operating medium therefrom, at least one support frame for eachside wall, each of said support frames being composed of structuralsteel elements and steel plates, support brackets connected to saidvertical tubes outside of the combustion chamber, said support framesresting on said brackets, and sliding connections slidably connectingsaid support frames to said vertical tubes and to said wall-formingtubes, each of said support frames including a lower horizontal channel,an upper horizontal channel spaced from said lower channel, and verticalelements interconnecting said channels, said lower channel resting onsaid support brackets and being vertically movably connected to saidwall-forming tubes, said upper channel being vertically movablyconnected to said vertical tubes and being vertically unmovablyconnected to said wall-forming tubes.

6. In a forced-flow steam generator as defined in claim 1 and whereineach of said structural steel elements is formed by a channel, uprightsbeing provided interconnecting said channels, and said plates beingplaced parallel to and filling the spaces between said uprights and saidchannels.

7. In a forced-flow steam generator as defined in claim 1 and whereineach of said vertical tubes is connected to one of said tubes bent inserpentine fashion for supplying operating medium thereto.

8. In a forced-flow steam generator as defined in claim 1 and whereinthe diameter of said vertical tubes is greater than that of said tubesbent in serpentine fashion.

References Cited in the file of this patent UNITED STATES PATENTS2,700,375 Godshalk et al Jan. 25, 1955 2,896,591 Schroedter July 28,1959 2,989,036 Hake et al June 20, 1961 2,999,483 Armacost Sept. 12,1961 3,030,937 Witzke Apr. 24, 1963 FOREIGN PATENTS 937,351 Germany Ian.5, 1956

1. IN A FORCED-FLOW STEAM GENERATOR COMPRISING A COMBUSTION CHAMBER OFANGULAR HORIZONTAL CROSS SECTION AND HAVING A PLURALITY OF SIDE WALLSAND CORNERS THEREBETWEEN, A SUPPORTING FRAMEWORK, SUBSTANTIALLY VERTICALTUBES PLACED IN EACH CORNER OF SAID COMBUSTION CHAMBER AND HUNG ON SAIDFRAMEWORK, A PLURALITY OF SAID VERTICAL TUBES BEING PLACED IN THE PLANEOF ONE OF THE SIDE WALLS EXTENDING FROM THE CORNER AND A PLURALITY OFSAID VERTICAL TUBES BEING PLACED IN THE PLANE OF THE SECOND SIDE WALLEXTENDING FROM SAID CORNER: TUBES BENT IN SERPENTINE FASHION PLACED INPLANES AND FORMING TUBE PANELS FORMING THE PARTS OF SAID SIDE WALLSBETWEEN SAID VERTICAL TUBES, AT LEAST ONE HORIZONTAL SUPPORT FRAME FOREACH SIDE WALL, EACH OF SAID SUPPORT FRAMES COMPRISING A HORIZONTALSTRUCTURAL STEEL ELEMENT AT THE UPPER END OF THE FRAME, A HORIZONTALSTRUCTURAL STEEL ELEMENT AT THE LOWER END OF THE FRAME, AND A STEELPLATE PLACED BETWEEN SAID STRUCTURAL STEEL ELEMENTS. SUPPORT BRACKETSCONNECTED TO SAID VERTICAL TUBES OUTSIDE OF THE COMBUSTION CHAMBER FORSUPPORTING ONE OF SAID STRUCTURAL STEEL ELEMENTS, SLIDING CONNECTIONSVERTICALLY SLIDABLY CONNECTING THE SECOND OF SAID STRUCTURAL STEELELEMENTS TO SAID VERTICAL TUBES, VERTICALLY SLIDABLE CONNECTIONS BETWEENSAID TUBE PANELS AND ONE OF SAID STRUCTURAL STEEL ELEMENTS ANDHORIZONTALLY SLIDABLE CONNECTIONS BETWEEN SAID TUBE PANELS AND THESECOND OF SAID STRUCTURAL STEEL ELEMENTS.